Assistant football coach Aaron Feis, cross country coach Scott Beigel and athletic director Chris Hixon, hailed as heroes, were among those killed during the shooting at Marjory Stoneman Douglas High School on Wednesday, officials confirmed Thursday.

"We had an athletic director, a campus monitor who responded immediately when there was signs of trouble in the school," Broward County Superintendent of Schools Robert W. Runcie said during a news conference Thursday. "Unfortunately those two heroes gave their lives for our kids and probably helped prevent this from being a worse tragedy than it is today."

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Cubs first baseman Anthony Rizzo issued condolences and encouragement while sounding a note of alarm over the shooting at his alma mater Wednesday that left at least 17 people dead. Warriors coach Steve Kerr said he's demoralized things haven't changed.

Police have said that at least 17 people were killed and more than a dozen were wounded in Wednesday's shooting in Parkland, Florida.

Head football coach Willis May told the Sun-Sentinel that a student told him that Feis, who also served as a security monitor at the school, pushed her out of the line of fire while jumping between her and the shooter.

Another student detailed how Beigel let students in the hallway into his classroom to keep them safe from the shooter. Beigel was shot and killed as he attempted to relock the door.

"He was my hero, and he will forever be my hero," student Kelsey Friend told CNN. "I'll never forget the actions he took for me and for fellow students in the classroom. He was an amazing person, and I am alive today because of him."

Also killed was senior Nicholas Dworet, a standout swimmer who had committed to the University of Indianapolis, a Division II school.

"Nick was an energetic and very vibrant kid," Indianapolis swimming and diving coach Jason Hite said in a statement. "He was very positive, lots of smiles when he was here on Jan. 20 for our big meet versus Grand Valley State and Lindenwood. He was on the sidelines cheering and was just a lot of fun. He fit in really well with everybody."

Expelled student Nikolas Cruz, 19, was charged with 17 counts of premeditated murder Thursday morning. Later in the day, the sheriff's department released a report saying Cruz confessed to carrying out the killings.

The Twitter account of the school's football team said Feis, who coached linemen, died while protecting students from the gunman.

It is with Great sadness that our Football Family has learned about the death of Aaron Feis. He was our Assistant Football Coach and security guard. He selflessly shielded students from the shooter when he was shot. He died a hero and he will forever be in our hearts and memories pic.twitter.com/O181FvuHl3

May told the Sun-Sentinel that Feis was the first to respond to the initial "code red" call on the school's security walkie-talkies. Feis was 37.

"I heard Aaron say, 'No, that is not firecrackers,'" May said. "That's the last I heard of him."

According to his biography on the school's athletic website, Feis graduated from Marjory Stoneman Douglas High School in 1999, returned to the school as a coach in 2002 and served as head coach of the junior varsity team for eight seasons. He also served as the school's college recruiting coordinator.

It said he lived in nearby Coral Springs with his wife and daughter.

"God takes good people, but that's the ones he needs," May later told the Miami Herald. "He got a good one in Feis."

Said Broward County Sheriff Scott Israel, whose two sons played for Feis: "When Aaron Feis died, when he was killed tragically, he did it protecting others because that is who Aaron Feis was.''

NFL commissioner Roger Goodell offered his condolences Thursday on behalf of "the entire football community" on Twitter.

The entire football community is grieving the loss of Coach Aaron Feis and all those who tragically lost their lives yesterday. https://t.co/geIMyMQ3Ld

"Big ol' teddy bear," May said of Feis to the Sun-Sentinel. "Hardcore -- he coached hard. Real good line. He did a great job with the [offensive] line. He took pride with working with those guys. Loyalty -- I trusted him. He had my back. He worked hard. Just a good man. Loved his family. Loved his brother. Just an excellent family man."

Hixon also served as the wrestling coach at Stoneman Douglas. He previously was athletic director at South Broward High School and had served in Iraq as a U.S. naval reservist. Hixon was 49.

"I was close to him," May told the Herald. "When he likes you and trusts you, you become friends. We were to that point where we were being able to trust each other. We had each other's back. He's a good person. He's good to people."

The married father of two had filled in as a volleyball coach and as a security monitor at Stoneman Douglas.

"He loved his family. He loved his job," friend and former colleague Dianne Sanzari told The Associated Press. "Chris was just amazing."

Maddy Wilford, a basketball player at Stoneman Douglas, was hospitalized after being shot multiple times with an AR-15, her mother posted on Facebook.

Girls' basketball coach Marilyn Rule also posted to Facebook early Thursday, saying Wilford has had two surgeries with another scheduled and is "fighting for her life."